My PRE Labour was just BHs that became stronger during the day. I'd also had some period-pain-like cramping the week before and some back pain,

My EARLY Labour was painful. The BHs went from being uncomfortable to painful and they became more regular. I dilated to 3cm in 15 hours of early labour, which I considered to be the painful contractions, not just the tightenings. The hospital considers early labour to be 0-4cm dilation, and established labour to be 4-10cm.

I think it's different for everyone, and obviously different depending on whether it's your first or subsequent baby.